(1) Field of the Invention
The present invention relates to a condensation catalyst and a catalytical condensation process in the presence of same. More particularly, the present invention relates to a condensation catalyst and a process for catalytically condensing organic carboxylic anhydrides, for example, phthalic anhydride, in the presence of the condensation catalyst to produce condensation products, for example, anthraquinone at a high yield and purity.
(2) Description of the Related Art
Various methods for producing anthraquinone are known, as follows.
(A) Anthracene is converted to anthraquinone by a catalytic oxidation method. This method is disadvantageous in that it is difficult to obtain a starting material consisting essentially of anthraquinone, and that the starting material contains a carcinogen.
(B) Anthraquinone is produced by a liquid phase Friedel-Crafts reaction of phthalic dianhydride with benzene in the presence of aluminum chloride (AlCl.sub.3) to produce o-benzoylbenzoic acid followed by acid cyclization. This method is disadvantageous in that a large amount of aluminum chloride, which is expensive, is consumed, and an excess of benzene is used.
(C) A gas phase Friedel-Crafts reaction method for producing anthraquinone from phthalic dianhydride with benzene was attempted, but a satisfactory catalyst and process for industrial working was not attained.
(D) As disclosed in Japanese Unexamined Patent Publication No. 57-38742 (1982) anthraquinone can be produced from 1,4-naphthoquinone and a small excess of 1,3-butadiene by a Diels-Alder reaction to give tetrahydroanthraquinone, followed by air oxidation in the presence of a base. This method is disadvantageous in that the procedures are complicated and phthalic anhydride is produced as a by-product.
(E) Indane compounds can be converted to corresponding anthraquinone compounds by a catalytical oxidation method. This method is disadvantageous in that the indane compound to be used as a starting material is expensive and harmful substances are produced as by-products.
(F) As disclosed in German Unexamined Patent Publication Nos. 2442911 and 2430567 diphenylmethane compounds can be converted to corresponding anthraquinone compounds by a catalytical oxidation method. This method comprises a plurality of steps and thus a long time is needed to complete the reaction.
(G) U.S. Pat. No. 3,932,474 discloses a process for producing anthraquinone by condensation of benzene with carbon monoxide (CO) in the presence of copper chloride (CuCl.sub.2). Namely, in this method, copper chloride must be used in a large amount.
(H) With respect to the liquid phase Friedel-Crafts reaction method for producing anthraquinone from phthalic dianhydride and benzene, U.S. Pat. No. 4,379,092 discloses a new method using a mixture of hydrogen fluoride (HF) and boron trifluoride (BF.sub.3) instead of aluminum chloride. Also, U.S. Pat. No. 4,666,532 discloses a new liquid phase Friedel-Crafts reaction method using a solid superstrong acid under pressure.
These methods, however, are disadvantageous in that the process steps are complicated and thus impractical for industrial working.
In view of the above-mentioned various methods for producing anthraquinone, the gas phase Friedel-Crafts reaction method is most preferable if a new catalyst having a high catalytic activity, durability and selectivity is attained, because the starting material is easily obtainable and cheap and the process is simple and can be carried out at a low cost.
Also, the new catalyst and process are obviously useful for the production of not only anthraquinone from phthalic dianhydride, and optionally, benzene, but also other organic compounds from other organic starting compounds.